Based on the machine translation of this Japanese page (last updated November 21, 2000)
All ATRAC1 will playback on any ATRAC1 machine. Over time the trend was to increase computing power used for music data encoding, but later versions also included techniques to improve sound quality on playback.
Note: ATRAC1 Written by any of the below chips will be compatible on playback. It does not mean that it cannot be played due to the difference in version. However, it may not be possible to play with the intended sound quality due to different versions. Playing a disc recorded with Version 4.5 with Version 1 does not produce the sound quality of Version 4.5. Also, even if a disc recorded with Version 1 is played back with Version 4.5, the sound quality of Version 4.5 will not be obtained.
Version 1
version feature
It is installed in the products released from 1993 (Autumn) to 1994 (Spring). The minimum recording unit of MD is 424 bytes per sound group as technically written. The sound of about 0.01 seconds is compressed and recorded in this 424 bytes, but Version 1 did not use all 424 bytes. In some places, I wrote the information twice in consideration of errors. In other words, I was using only 212 bytes . This 424 bytes does not have to be used absolutely, but the ATRAC development side can freely set the usage amount. At that time, I was writing compressed information, so I was worried about errors and wrote twice. Of course, the amount of information was small, so the sound quality was the worst. (The audio data aria can be used not only for “audio data”, but also for areas that are resistant to errors and areas that are controlled, that is, redundant data blocks that prevent mistakes when reading and writing. It is not necessary to make this part because the standard says “it is okay to make it.”) This negative impact has turned away from pure audiophiles, and it seems that it is still trailing.
Version 2
version feature
It is installed in the products released from 1994 (spring) to 1995 (autumn). Since the technology is stable, there is no need to write twice. In other words, it became possible to use the full 424 bytes in about 0.01 seconds. In other words, the sound quality has improved due to the expansion of the amount of information. At this stage, it can be said that ATRAC has reached the competent standard sound quality. Also, this expansion of information (using all 424 bytes) has been inherited by all since then.
Version 3
version feature
(CXD2536) It is installed in the ones released from 1995 (spring) to 1997 (summer). The number of models released from this Version 3 has increased, but it did not sell explosively. MD was still an expensive class of audio systems, so it didn't gain momentum. The portability hasn't changed much compared to the version 2 period, so it may have been a modest era. This Version 3 is still portable and is an active ATRAC. The computing power of ATRAC-DSP is 24 Bit . It is equipped with two I / O ports, 20 bits for digital input / output, and 24 bits for data input / output with the A / D / D / A converter.
Version 3.5
version feature
It is installed in the products released from 1995 (Autumn) to 1997 (Summer). The time when it appeared is the same as Version 3. For some reason, this is obvious when you look at the machines that have Version 3.5 installed. All are stationary machines or component machines. In other words, it is an upgraded version of Version 3 for systems (stationary machines) that require high sound quality. In particular, the computing power (encoding) during recording has been greatly improved. The computing power of ATRAC-DSP is 24 Bit .
Version 4
version feature
(CXD2650) It is installed in the products released from 1996 (summer / autumn) to 1998 (present). By this time, machines of all styles have appeared from all manufacturers, and as a result, they are portable and play for a long time due to the principle of competition. , Accelerating the price reduction, it became popular at once. The number of units sold in 1997 has overtaken the portable cassette. So, this Version 4 is basically installed in the deck type system (reference), and it is not adopted in the system like portable. The computing power of ATRAC-DSP is 24 Bit .
Version 4.5
version feature
(CXD2654) It is installed in the products released from 1996 (winter) to 1998 (present). By adopting adaptive high frequency control , it has higher precision computing power than Version 4 and the sound quality is further improved. The audition feel is pretty close to a CD, and it's hard to tell unless you use a proper system. The computing power of ATRAC-DSP is 24 Bit, and the bit width of I / O is 20 Bit .
Version Type-R
version feature
(CXD2656) It has been installed in SONY decks since 1998 (summer). Is it okay to call this version? ATRAC is different from the previous version series. The technology has inherited Version 4.5, and along with adaptive wide area control, the computing power around other circuits has been doubled, but 24-bit operations are not 48-bit operations. The expression of the algorithm has improved and compression closer to the original sound has become possible. In fact, it's no exaggeration to say ATRAC Version 5 . (Answer from Sony) The computing power of ATRAC-DSP is 24 Bit, and the bit width of I / O is 20 Bit . Portable MDLP compatible ATRAC ATRAC-DSP installed from the “MZ-R900” released in the summer of 2000 The position seen from the above version is unknown. It is presumed that it has a built-in ATRAC3 circuit that draws the blood of portable Ver.3 (or Ver.4). A 0.18 μm process thin system LSI consisting of low power consumption, ATRAC / ATRAC3 integration, 32bit RISC processor, etc. </WRAP>
High-quality sound technology is added to the existing ATRAC! It is closer to the original sound while being compatible with other versions . ARTIST SYSTEM (formerly ASRAC)
It has been installed on Pioneer decks since 1998 (Summer). ATRAC-DSP installed in Pioneer's single deck and MD component “FILL”. ARTIST-SYSTEM (ASRAC) is basically divided into an ATRAC section and a DSP signal analysis section that handles music signal preprocessing . The input digital music signal is subjected to frequency analysis, and a masking database is created so that more audible audio signals remain when ATRAC later selects audible audio signals. Then, the masking database is transferred to the ATRAC section, and compressed data is created based on that information. ARTIST-SYSTEM (ASRAC) is an algorithm that uses ATRAC-only algorithms to analyze music signals by pre-processing and create higher-density data . Compatibility with other systems is maintained for decoding (decompression).
It seems that the MD system (including OEM) developed by Sharp is equipped with ATRAC customized by Sharp, which is different from the above . (Details are under investigation … I don't know.) It is presumed that Sharp X is ATRAC with the same function as Version X when compared from the time. However, it seems that something is different from the time Sharp 5 came out. (It seems that it is not treated as a decimal point) Sharp 1 ?? Sharp 2 ?? Sharp 3 There are two types, “for recording / playback” and “for playback only”. Until a while ago, I used to use ATRAC for recording and playback not only for recording / playback machines but also for “ playback-only machines ” . Since ATRAC-DSP development costs a certain amount, it was better to divert the recording / playback to the playback-only machine than to develop the playback-only machine, but recently, “miniaturization” and “low power” “Playback-only ATRAC” has been developed and adopted to realize this. It is said that the capability of this play-only ATRAC is equivalent to that of the 3rd generation. MD playback does not depend on the ATRAC version, so even the 3rd generation is sufficient. It is presumed that the “playback section” of ATRAC for recording and playback after this has basically not changed. Sharp 4 It is installed in the products released from 1996 (summer) to 1998 (present). It has a computing power of 20 Bit. Play-only Sharp 4 ATRAC-DSP created by a 0.25 μm process with a built-in ATRAC3 decoder for MDLP playback in addition to the ATRAC normal ATRAC installed in the MD-ST77 that appeared in the fall of 2000 . The computing power of normal ATRAC is 22 Bit. Sharp 5 It is installed in the products released from 1997 (spring) to 1998 (present). ATRAC with 24-bit computing power. This “Sharp 5” was initially installed in component machines, but recently it has also been installed in portable machines. However, if you think that all models will move to Sharp 5, it seems that the recently released “SHARP MD-SS311 / 312” is equipped with Sharp 4. Sharp 6 It will be installed in the “MD-MS722” released in 1998 (summer). ATRAC with 24-bit computing power. Adoption of a three-dimensional ( time axis direction / frequency axis direction / amplitude direction) adaptive bit allocation algorithm. By changing the fixed time, frequency, and amplitude axes according to the characteristics of the sound, it is possible to compress more audible voice. However, these are processed at the time of compression (recording), and even if you play the compressed version with Sharp 6 with Sharp 6, this function does not dramatically improve the sound.
Sharp 7 It is installed in the one released in 1998 (summer). Realized low power consumption based on the 6th generation. ATRAC performance is the same as the 6th generation.
Sharp 8.3 It has been installed since 2000 (Autumn) “MD-MT77”. Built-in ATRAC3 which is MDLP based on the 7th generation. ATRAC (normal mode) Performance is the same as the 6th generation.
Developed by Sanyo. Sanyo's IC device division is large and supplies IC devices for all types of equipment to each companyAmong them are ATRAC devices. Currently, as far as I know, there are three types of ATRAC devices. One is a portable ATRAC decoder. This is for playback-only portable machines and has only ATRAC decoding capability. The second is an ATRAC decoder for car stereos . Like a portable device, it is a playback-only device, but it is also a device that considers CD playback because it is a car stereo. When playing a CD, the ATRAC circuit is not used, only the D / A conversion circuit is used. This chip also seems to support CD-TEXT. And the last is ATRAC for portable recording and reuse . This device seems to have been developed later than the above two types. Is it still difficultOf course, you can ATRAC convert a linear PCM signal and vice versa. There is no doubt that it is installed in the “ MD-U4 ”. MD device “LC89640”
Just like Pioneer, add your own high-quality sound technology to ATRAC! HDES “HDES” (High Density Encoding System) Panasonic's original audio compression technology that complies with ATRAC. A rich sound field reproduction is realized by realizing finer nuances. The computing power of ATRAC-DSP is 24 bits.
1. High-density bit allocation
Achieves a wide range of sound by performing arithmetic processing that emphasizes low and high frequencies.
2. Reduction of pre- echo noise Noise is reduced by optimizing the processing time unit when noise (pre-echo noise) occurs at the time of sudden rise of sound, and sound closer to the original sound can be reproduced to enjoy clear sound.
3. High-precision quantized recording is possible with high-precision analog-to-digital conversion during recording.